There is a growing interest in drivers others than lasers to compress and ignite small quantities of thermonuclear fuel for the release of energy by inertial confinement. The reason for this search of alternative drivers are the inherent disadvantages of laser fusion. One of these disadvantages is the comparatively long wave length of laser light and which is not well matched to the plasma frequency at the desired high target densities which shall be reached by implosive compression. Lasers furthermore suffer from low efficiency and high cost. Finally, the problem of stimulated Brillouin backscattering from the target sets an upper limit for the laser power. Other driver options presently under study include beams of charged particles ranging from electrons to heavy ions and even projectiles accelerated to hypervelocities. However, the very large requirements in beam power combined with good beam focusing is likely to make any one of these alternative concepts also rather expensive.
In case the ignition is done with heavy ion beams generated by conventional particle accelerators, the length of these accelerators will be many km. The same is true for the concept of impact fusion by the magnetic acceleration of a small superconducting solenoid to hypervelocities.
The original proposals for several of these alternative driver concepts, for example the pulsed acceleration of an intense beam of ions by a magnetically insulated diode, were made by the inventor a long time ago.